What is the percentage of void space in $hcp$ and $ccp$ structures (in $\%$)?

$A$ compound is formed by two elements $M$ and $N$. The element $N$ forms $ccp$ lattice and atoms of $M$ occupy $1/3$ of the tetrahedral voids. What is the formula of the compound?

How many tetrahedral voids are present in $0.4 \ mol$ of a compound that forms an $hcp$ structure?

Give two examples of metals that crystallize in the $hcp$ (hexagonal close-packed) structure.

An ionic compound is formed by elements $X$ and $Y$. Element $Y$ forms a face-centered cubic $(FCC)$ lattice, and element $X$ occupies one-third of the tetrahedral voids. What is the formula of the compound?

In an ionic solid compound,$A$ ions are at the corners of the cube and $B$ ions are at the center of each face. The molecular formula of the compound will be ..............